500 error on showing not existed commit fixed

app/controllers/commit_controller.rb

@@ -11,7 +11,11 @@ class CommitController < ProjectResourceController
     result = CommitLoadContext.new(project, current_user, params).execute
 
     @commit = result[:commit]
-    git_not_found! unless @commit
+    
+    if @commit.nil?
+      git_not_found!
+      return
+    end
 
     @suppress_diff = result[:suppress_diff]